The present invention relates to a graphic drawing method and system using coordinate input means, and more particularly to a graphic drawing method and system suitable for forming a composite graphic composed of a combination of fundamental graphics.
With high performance work stations widely used as office automation machines, it has become possible for an operator to interactively display a graphic on a display screen by using a pointing device such as a mouse.
In graphic data processing, not only can a fundamental graphic such as a straight line, a rectangular, a circle and the like be drawn, but also an optional graphic composed of a combination of fundamental graphics can be is drawn. For instance, in drawing a corner rounded rectangular composed of straight lines and circular arcs, it is difficult to make the end point of a straight line to correctly superpose upon the end point of a circular arc.
Some of composite graphics drawn in this manner are occasionally subjected to magnification/reduction or the like. In such a case, even if the end points of a composite graphic appear correctly superposed on the display screen, after the magnification/reduction, the shape of the composite graphic may deform. Deformity includes end points that are separated or line segments that are intersected.
To solve the above problems, a method has been proposed whereby a grid is displayed on the display screen. By using a so-called grid lock function, an input coordinate point is forced to superpose upon an intersected point of the grid. This method, however, poses a fatal problem. Such a function cannot be used without displaying the grid so the method is not versatile.